/*
 * ldisc.c: PuTTY line discipline. Sits between the input coming
 * from keypresses in the window, and the output channel leading to
 * the back end. Implements echo and/or local line editing,
 * depending on what's currently configured.
 */

#include <stdio.h>
#include <ctype.h>

#include "putty.h"
#include "terminal.h"
#include "ldisc.h"

void lpage_send(void *handle, int codepage, char *buf, int len, int interactive)
{
    Ldisc ldisc = (Ldisc) handle;
    wchar_t *widebuffer = 0;
    int widesize = 0;
    int wclen;

    if (codepage < 0)
    {
        ldisc_send(ldisc, buf, len, interactive);
        return;
    }

    widesize = len * 2;
    widebuffer = snewn(widesize, wchar_t);

    wclen = mb_to_wc(codepage, 0, buf, len, widebuffer, widesize);
    luni_send(ldisc, widebuffer, wclen, interactive);

    sfree(widebuffer);
}

void luni_send(void *handle, wchar_t *widebuf, int len, int interactive)
{
    Ldisc ldisc = (Ldisc) handle;
    int ratio = (in_utf(ldisc->term)) ? 3 : 1;
    char *linebuffer;
    int linesize;
    int i;
    char *p;

    linesize = len * ratio * 2;
    linebuffer = snewn(linesize, char);

    if (in_utf(ldisc->term))
    {
        /* UTF is a simple algorithm */
        for (p = linebuffer, i = 0; i < len; i++)
        {
            unsigned long ch = widebuf[i];

            if ((ch & 0xF800) == 0xD800)
            {
#ifdef PLATFORM_IS_UTF16
                if (i + 1 < len)
                {
                    unsigned long ch2 = widebuf[i + 1];
                    if ((ch & 0xFC00) == 0xD800 && (ch2 & 0xFC00) == 0xDC00)
                    {
                        ch = 0x10000 + ((ch & 0x3FF) << 10) + (ch2 & 0x3FF);
                        i++;
                    }
                }
                else
#endif
                {
                    /* Unrecognised UTF-16 sequence */
                    ch = '.';
                }
            }

            if (ch < 0x80)
            {
                *p++ = (char) (ch);
            }
            else if (ch < 0x800)
            {
                *p++ = (char) (0xC0 | (ch >> 6));
                *p++ = (char) (0x80 | (ch & 0x3F));
            }
            else if (ch < 0x10000)
            {
                *p++ = (char) (0xE0 | (ch >> 12));
                *p++ = (char) (0x80 | ((ch >> 6) & 0x3F));
                *p++ = (char) (0x80 | (ch & 0x3F));
            }
            else
            {
                *p++ = (char) (0xF0 | (ch >> 18));
                *p++ = (char) (0x80 | ((ch >> 12) & 0x3F));
                *p++ = (char) (0x80 | ((ch >> 6) & 0x3F));
                *p++ = (char) (0x80 | (ch & 0x3F));
            }
        }
    }
    else
    {
        int rv;
        rv = wc_to_mb(ldisc->term->ucsdata->line_codepage, 0, widebuf, len,
                      linebuffer, linesize, NULL, NULL, ldisc->term->ucsdata);
        if (rv >= 0)
            p = linebuffer + rv;
        else
            p = linebuffer;
    }
    if (p > linebuffer)
        ldisc_send(ldisc, linebuffer, p - linebuffer, interactive);

    sfree(linebuffer);
}
